Stent

ABSTRACT

In one embodiment according to the present invention, a stent is described having a generally cylindrical body formed from a single woven nitinol wire. The distal and proximal ends of the stent include a plurality of loops, some of which include marker members used for visualizing the position of the stent. In another embodiment, the previously described stent includes an inner flow diverting layer.

RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 15/784,052 filed Oct. 13, 2017 entitled Stent,which is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/311,430 filed Dec. 5, 2011 entitled Stent (nowU.S. Pat. No. 9,867,725 issued Jan. 16, 2018), which claims benefit ofand priority to U.S. Provisional Patent Application Ser. No. 61/422,604filed Dec. 13, 2010 entitled Stent; to U.S. Provisional PatentApplication Ser. No. 61/425,175 filed Dec. 20, 2010 entitled PolymerStent And Method Of Manufacture; to U.S. Provisional Patent ApplicationSer. No. 61/427,773 filed Dec. 28, 2010 entitled Polymer Stent AndMethod Of Manufacture 2; and which is a continuation-in-part of U.S.Nonprovisional Patent Application Ser. No. 13/003,277, 371 date Aug. 23,2012, entitled Stent (now abandoned), which is the U.S. National Phaseof and claims priority to International Patent Application No.PCT/US2010/061627 filed Dec. 21, 2010 entitled Stent; all of which arehereby incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The present invention relates to devices for the treatment of bodycavities, such as the embolization of vascular aneurysms and the like,and methods for making and using such devices.

The occlusion of body cavities, blood vessels, and other lumina byembolization is desired in a number of clinical situations. For example,the occlusion of fallopian tubes for the purposes of sterilization, andthe occlusive repair of cardiac defects, such as a patent foramen ovale,patent ductus arteriosis, and left atrial appendage, and atrial septaldefects. The function of an occlusion device in such situations is tosubstantially block or inhibit the flow of bodily fluids into or throughthe cavity, lumen, vessel, space, or defect for the therapeutic benefitof the patient.

The embolization of blood vessels is also desired to repair a number ofvascular abnormalities. For example, vascular embolization has been usedto control vascular bleeding, to occlude the blood supply to tumors, andto occlude vascular aneurysms, particularly intracranial aneurysms.

In recent years, vascular embolization for the treatment of aneurysmshas received much attention. Several different treatment modalities havebeen shown in the prior art. One approach that has shown promise is theuse of thrombogenic microcoils. These microcoils may be made ofbiocompatible metal alloy(s) (typically a radio-opaque material such asplatinum or tungsten) or a suitable polymer. Examples of microcoils aredisclosed in the following patents: U.S. Pat. No. 4,994,069—Ritchart etal.; U.S. Pat. No. 5,133,731—Butler et al.; U.S. Pat. No. 5,226,911—Cheeet al.; U.S. Pat. No. 5,312,415—Palermo; U.S. Pat. No. 5,382,259—Phelpset al.; U.S. Pat. No. 5,382,260—Dormandy, Jr. et al.; U.S. Pat. No.5,476,472—Dormandy, Jr. et al.; U.S. Pat. No. 5,578,074—Mirigian; U.S.Pat. No. 5,582,619—Ken; U.S. Pat. No. 5,624,461—Mariant; U.S. Pat. No.5,645,558—Horton; U.S. Pat. No. 5,658,308—Snyder; and U.S. Pat. No.5,718,711—Berenstein et al.; all of which are hereby incorporated byreference.

Stents have also been recently used to treat aneurysms. For example, asseen in U.S. Pat. No. 5,951,599—McCrory and U.S. Pub. No.2002/0169473—Sepetka et al., the contents of which are incorporated byreference, a stent can be used to reinforce the vessel wall around theaneurysm while microcoils or other embolic material are advanced intothe aneurysm. In another example seen in U.S. Pub. No.2006/0206201—Garcia et al. and also incorporated by reference, a denselywoven stent is placed over the mouth of the aneurysm which reduces bloodflow through the aneurysm's interior and ultimately results inthrombosis.

SUMMARY OF THE INVENTION

In one embodiment according to the present invention, a stent isdescribed having a generally cylindrical body formed from a single wovennitinol wire. The distal and proximal ends of the stent include aplurality of loops, some of which include marker members used forvisualizing the position of the stent.

In another embodiment according to the present invention, a deliverydevice is described, having an outer catheter member and an inner pushermember disposed in a passage of the catheter. The distal end of thepusher member includes a distal and proximal marker band that is raisedabove the adjacent portions of the pusher member body. The previouslydescribed stent can be compressed over the distal marker band such thatthe stent's proximal loops and proximal marker members are disposedbetween the distal and proximal marker bands on the pusher member.

In one example, the delivery device can be used to deliver thepreviously described stent over an opening of an aneurysm. The aneurysmis preferably first filled with microcoils or embolic material eitherbefore or after delivery of the stent.

In another embodiment according to the present invention, a dual layerstent is described having an outer anchoring stent similar to thepreviously described stent and a discrete inner mesh layer formed from aplurality of woven members. The proximal end of the outer stent and theinner stent are connected together by connecting members or crimping,allowing the remaining portions of the outer anchoring stent and innermesh layer to independently change in length as each begins to expand indiameter. Alternately, the inner mesh layer may only extend along aportion of the length of outer stent and may be symmetrically orasymmetrically positioned between the out stent's distal and proximalends.

In one example, the dual layer stent can be delivered over the openingof an aneurysm to modify the flow of blood that enters the aneurysm. Asthe blood flow into the aneurysm becomes stagnant, a thrombosis forms toblock up the interior aneurysm space.

In another embodiment according to the present invention, a single ordual layer stent can be created by polymerizing a prepolymer liquidinside a tube, syringe or similar structure. Patterns can be created inthe polymer structure via a pre-patterned mandrel on which the polymerstructure is polymerized or by cutting the polymer structure afterpolymerization.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which:

FIG. 1 illustrates a side view of a stent according to a preferredembodiment of the present invention;

FIG. 2 illustrates a front view of the stent of FIG. 1;

FIG. 3 illustrates a magnified view of area 3 in FIG. 1;

FIG. 4 illustrates a magnified view of area 4 in FIG. 1;

FIG. 5 illustrates a magnified view of area 5 in FIG. 1;

FIG. 6 illustrates a magnified view of area 6 in FIG. 1;

FIG. 7 illustrates a side view of a pusher member according to apreferred embodiment of the present invention;

FIG. 8 illustrates a partial cross sectional view of the pusher memberof FIG. 7 having the stent of FIG. 1 compressed over its distal end andbeing positioned in a catheter;

FIG. 9 illustrates the stent of FIG. 1 positioned over the opening of ananeurysm;

FIG. 10 illustrates a side view of a mandrel according to the presentinvention that can be used to create the stent of FIG. 1;

FIG. 11 illustrates a side view of a stent according to a preferredembodiment of the present invention;

FIGS. 12-14 illustrate various views of a dual layer stent according toa preferred embodiment of the present invention;

FIG. 15 illustrates a cross sectional view of a delivery system for thedual layer stent of FIGS. 12-14;

FIG. 16 illustrates a perspective view of dual layer stent having anouter stent layer formed from a tube or sheet of material;

FIG. 17 illustrates a cross sectional view of the dual layer stent ofFIG. 15 showing various optional attachment points of both layers of thedual layer stent;

FIG. 18 illustrates another preferred embodiment of a dual layer stentaccording to the present invention;

FIG. 19 illustrates a stent according to the present invention composedof a flow-diverting layer;

FIG. 20 illustrates a dual layer stent according to the presentinvention having a shortened flow-diverting layer;

FIG. 21 illustrates a dual layer stent according to the presentinvention having an elongated flow-diverting layer;

FIG. 22 illustrates a dual layer stent according to the presentinvention having an asymmetrically positioned flow-diverting layer;

FIGS. 23 and 24 illustrate an expansile wire for use with aflow-diverting layer according to the present invention;

FIG. 25 illustrates a portion of a flow-diverting layer having anexpansile wire incorporated into its structure;

FIG. 26-29 illustrate a process according to the present invention forcreating a polymer stent or stent layer;

FIG. 30 illustrates another process according to the present inventionfor creating a polymer stent or stent layer; and,

FIGS. 31-36 illustrate another process according to the presentinvention for creating a polymer stent or stent layer.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 illustrates a stent 100 according to a preferred embodiment ofthe present invention. The stent 100 is woven or braided together from asingle wire 102 to form a generally cylindrical shape with a pluralityof loops 104 around the perimeter of both ends of the stent 100.

As seen in area 5 in FIG. 1 and in FIG. 5, the ends of the single wire102 can be connected to each other via welding (see welded region 116),bonding agents or a similar adhesive mechanism. Once the ends are weldedor bonded, the wire 102 has no “free” ends.

Each of the loops 104 may contain one or more coil members 106.Preferably, the coil members 106 are disposed around the wire 102 of theloops 104 which, as discussed in greater detail below, denote theproximal and distal ends of the stent 100. Additionally, these coilmembers 106 may provide additional anchoring force within a deliverydevice as described in greater detail below.

In one example, a distal end of the stent 100 includes at least twoloops 104 with two coil members 106 each and a proximal end of the stent100 includes at least two loops 104 with one coil member 106 each.However, it should be understood that the stent 100 can include anynumber of coil members 106 on any number of loops 104.

Preferably, these coil members 106 are positioned near a center area ofthe loop 104, such that when the stent 100 is in a collapsed state, thecoil members 106 are positioned near the very distal or very proximalend of the stent 100.

Preferably, each coil member 106 is composed of a wire 105 wound arounda portion of the loop 104. Each coil member 106 can be composed of adiscrete wire 105 (as seen in FIG. 3) or a single wire 105 can formmultiple coil members 106 (as seen in FIGS. 1, 3 and 6). In the presentpreferred embodiment, some coil members 106 are composed of discretesections of wire 105 while other coil members 106 on either end areformed from the same, continuous wire 105. As seen in FIG. 1, the wire105 can connected to coil members 106 on each end of the stent 100 bybeing located within the inner portion or lumen of the stent 100.Alternately, the wire 105 may be woven into the wires 102 of the stent100.

Preferably, the wire 105 of the coil members 106 is composed of aradiopaque material such as tantalum or platinum. The wire 105preferably has a diameter of about 0.00225″.

Alternately, the coil members 106 may be a radiopaque sleeve that isdisposed on and adhered to the loop 104.

In one embodiment, the loops 104 on the proximal end of the stent 100have one coil 106 on each side of the loop 104 (as seen in FIG. 3) whilethe distal end of the stent 100 includes only one coil 106 on one sideof each loop 104 (as seen in FIG. 6).

Preferably, the weaving pattern of the stent 100 prevents the distalcoils 106 from being exposed or “sticking up” from an outer diameter ofthe stent 100 during retraction. Hence, if the user decides to retractthe stent 100 back into the catheter for repositioning and redeployment,the distal coils 106 will not catch or contact the distal edge of thecatheter, thereby minimizing damage to the stent 100 that mightotherwise occur during retraction.

One specific technique for minimizing the exposure of the distal coils106 during retraction is to weave the stent 100 such that portions ofthe wire 102 overlap (i.e., are positioned at a greater outer diameterposition) than the side of the loop 104 with coil 106. As seen in FIG.6, some smaller, minor loops 107 are woven to overlap a first side 104Aof the loop 104 that includes the coil 106 (see location 109) whileother minor loops 107 are woven underneath a second side 104B of theloop 104 (see location 111).

As a user retracts the stent 100 back into the catheter, the minor loops107 move inward (i.e., towards the center of the stent's passage) as thestent 100 compresses in diameter, thereby inwardly pressing on the firstside 104A of the loop 104. In this respect, the minor loops 107 exertinward or compressive force on the first side 104A of the loop 104. Thisconfiguration ensures that the first side 104A of the loop 104 andtherefore the coil 106 is not positioned at an outermost diameter of thestent 100 during retraction and therefore reduces the likelihood of thecoils 106 of catching or hooking on to the distal end of the deploymentcatheter.

As seen best in FIG. 1 and FIG. 2, the loops 104 are flared or biased toan outer diameter 114 when fully expanded relative to the diameter ofthe main body of stent 100. These loops 104 can also expand to adiameter that is even with or smaller than that of the main body.

The stent 100 preferably has a diameter 110 sized for a vessel 152 inthe human body, as seen in FIG. 9. More preferably, the diameter 110 isbetween about 2 mm and 10 mm. The length of the stent 100 is preferablysized to extend beyond the mouth of an aneurysm 150 as also seen in FIG.9. More preferably, the length of the stent 100 is between about 5 mmand 100 mm.

FIGS. 7 and 8 illustrate a delivery system 135 according to the presentinvention which can be used to deliver the stent 100. A catheter orsheath 133 is positioned over a delivery pusher 130, maintaining thestent 100 in its compressed position. Once the distal end of the sheath133 has achieved a desired target location (i.e., adjacent an aneurysm150), the sheath 133 can be retracted to release the stent 100.

The delivery pusher 130 is preferably composed of a core member 132,which tapers in diameter near its distal end (made from nitinol). Aproximal area of the tapered end of the core member 132 includes alarger diameter first wire coil 134 that is preferably made fromstainless steel and welded or soldered in place on the core member 132.Distal to the coiled wire is a first marker band 136 that is fixed tothe core member 132 and preferably made from a radiopaque material suchas platinum.

A smaller diameter second wire coil 138 is located distal to the markerband 136 and is preferably made from stainless steel or plastic sleeve.A second marker band 140 is located distal to the second wire coil 138and is also preferably made from a radiopaque material such as platinum.Distal to the second marker band 140 is a narrow, exposed section 142 ofthe core member 132. Finally, a coiled distal tip member 144 is disposedon the distal end of the core member 132 and is preferably composed of aradiopaque material such as platinum or tantalum.

In one example, the inner diameter of the sheath 133 is about 0.027″ andabout 1 meter in length. The delivery pusher 130 is also about 2 metersin length. The sections of the delivery pusher 130 preferably have thefollowing diameters: the proximal region of the core member 132 is about0.0180 inch, the first wire coil 134 is about 0.0180 inch, the firstmarker band 136 is about 0.0175 inch, the second wire coil 138 is about0.0050 inch, the second marker band 140 is about 0.0140 inch, the distalcore member section 142 is about 0.003 inch, and the distal tip member144 is about 0.0100 inch. The sections of the delivery pusher 130preferably have the following lengths: the proximal region of the coremember 132 is about 1 meter, the first wire coil 134 is about 45 cm, thefirst marker band 136 is about 0.020 inch, the second wire coil 138 isabout 0.065 inch, the second marker band 140 is about 0.020 inch thedistal core member section 142 is about 10 cm, and the distal tip member144 is about 1 cm.

As seen in FIG. 8, the stent 100 is compressed over the distal end ofthe delivery pusher 130 such that the coil members 106 on the proximalend of the stent 100 are positioned between the first marker band 136and the second marker band 140. Preferably, the proximal coil members106 are not in contact with either marker band 136 or 140 and aremaintained via frictional forces between the sheath 133 and the secondcoiled area 138.

When the distal end of the delivery pusher has reached an area adjacenta desired target location (e.g., near an aneurysm), the sheath 133 isretracted proximally relative to the delivery pusher 130. As the sheath133 exposes the stent 100, the stent 100 expands against the walls ofthe vessel 152, as seen in FIG. 9.

The stent 100 can also be retracted (if it was not fullydeployed/released) by retracting the pusher 130 in a proximal direction,thereby causing the marker band 140 to contact the proximal marker bands106, pulling the stent 100 back into the sheath 133.

In one exemplary use, the stent 100 can be delivered over the opening ofan aneurysm 150 after embolic devices or material, such as emboliccoils, have been delivered within the aneurysm 150. In this respect, thestent 100 helps prevent the treatment devices from pushing out of theaneurysm 150 and causing complications or reducing efficacy of thetreatment.

In one example, the wire 102 is composed of a shape-memory elasticmaterial such as nitinol between about 0.001 inch and 0.010 inch indiameter.

The wire 102 may also vary in diameter over the length of the stent 100.For example, the diameter of the wire 102 near the proximal and distalends may be thicker than that of the middle portion of the stent 100. Inanother example, the proximal and distal ends may be thinner than themiddle portion. In another example, the diameter of the wire 102 mayalternate between larger and smaller diameters along the length of thestent 100. In yet another example, the diameter of the wire 102 maygradually increase or decrease along the length of the stent 100. In yetanother example, the loops 104 may be composed of wire 102 having alarger or smaller diameter than that of the wire 102 comprising the mainbody of the stent 100. In a more detailed example, the diameter of thewire 102 of the loops 104 may be about 0.003 inch while the wire 102 ofthe body of the stent 100 may be about 0.002 inch.

In yet another example, select areas of the wire 102 may have a reducedthickness where the wire 102 may cross over another section in acompressed and/or expanded configuration of the stent 100. In thisrespect, the thickness of the stent 100 can be effectively reduced incertain configurations. For example, if sections of the wire 102 werereduced at areas where the wire 102 overlapped when in a compressedconfiguration, the overall profile or thickness of the stent 100 can bereduced, allowing the stent 100 to potentially fit into a smallerdelivery catheter.

This variation in diameter of the wire 102 can be achieved byelectropolishing, etching or otherwise reducing portions of theassembled stent 100 to cause a diameter reduction. Alternately, regionsof the wire 102 can be reduced prior to being wound or woven into theshape of the stent 100. In this respect, a desired weaving pattern canbe determined, the desired post-weaving, reduced-diameter regions can becalculated and reduced, and finally the stent 100 can be woven with themodified wire 102.

In another variation, the pre-woven wire 102 can be tapered along asingle direction and woven together to form the stent 100.

In one exemplary preparation, a 0.0035 inch diameter nitinol wire iswound or woven over a mandrel 160. As seen in FIG. 10, the mandrel 160may have three pins 162, 164, 166 extending through each end, such thata portion of each end of each pin extends out from the body of themandrel 160. The wire 102 begins at one pin, and then is wound 3.0625revolutions clockwise around the body of the mandrel 160. The wire 102is bent around a nearby pin, then wound 3.0625 revolutions clockwiseback towards the other side of the mandrel 160, passing over and underthe previously wound section of wire 102. This process is repeated untileight loops are formed on each end.

In another example, the mandrel 160 may have 8 pins and the wire 102 iswound 2.375 revolutions. In another example, the mandrel 160 may have 16pins and the wire 102 is wound 3.0625 revolutions. In yet anotherexample, the mandrel may have between 8 and 16 pins and is wound between2.375 and 3.0625 revolutions.

Once wound, the stent 100 is heat-set on the mandrel 160, for example,at about 500° C. for about 10 minutes. The two free ends of the nitinolwire can be laser welded together and electro-polished such that thefinal wire diameter is about 0.0023 inch.

Finally, the radiopaque wire 105 of about 0.00225 inch in diameter iswound onto different areas of the stent loops 104, forming coil members106. Preferably, the wire 105 is wound for about 0.04 inch in length tocreate each coil member 106.

In another embodiment, the stent 100 can be formed from a plurality ofdiscrete wires instead of a single wire 102. The ends of this pluralityof wires can be left free or can be welded, adhered or fused togetherfor form loops 104. In another embodiment, the stent 100 can be formedby laser cutting, etching, machining or any other known fabricationsmethods.

The wire 102 is preferably composed of a shape memory metal such asNitinol. Optionally, this shape memory metal can include a variety ofdifferent therapeutic coatings or a hydrogel coating that swells orexpands when exposed to blood. The wire 102 can also be composed of abiocompatible polymer material (e.g., PET) or from a hydrogel material.

FIG. 11 illustrates an embodiment of a stent 190 that is similar to thepreviously described stent 100, except that each end of the stent 190includes three loops 104 instead of the four loops 104 of the previousstent 100. Additionally, the radiopaque wire 105 that form each of thecoils 106 is also preferably woven into the stent 190, connecting atleast some of the coils 104 on each end of the stent 190. Finally, thewire 102 is woven back and forth about 12 times along the length of thestent 190.

FIG. 12 illustrates a preferred embodiment of a dual layer stent 200according to the present invention. Generally, the dual layer stent 200includes an outer anchoring stent 100 that is similar to the previouslydescribed stent 100 seen in FIGS. 1-9. The dual layer stent 200 alsoincludes an inner flow-diverting layer 202 that is disposed within theinner lumen or passage of the anchoring stent 100.

Often, stents with relatively small wires do not provide adequateexpansile forces and therefore do not reliably maintain their positionat a target location. Additionally, prior art woven stents created withmany wires can have free ends that can poke or damage a patient'svessel. In contrast, larger wires are difficult to weave tightly enough(i.e., large spaces between adjacent wires) to modify blood flow at adesired location. The stent 200 seeks to overcome these disadvantages byincluding both the larger wire braid anchoring stent 100 to provide adesired anchoring force and the smaller wire braid flow-diverting layer202 to divert blood.

In one example, the flow-diverting layer 202 is composed of at least 32wires 204 that are between about 0.0005 to about 0.002 inch in diameterand made from a memory elastic material such as nitinol. These wires 204are woven or braided together in a tubular shape having a pore size lessthan 0.010 inch. Preferably, this braiding is achieved with a braidingmachine, which is known in the art and can braid the wires 204 in aregular pattern such as a diamond shaped pattern.

The flow-diverting layer 202 can have areas of its wire 204 that have areduced diameter, similar to the patterns and techniques previouslydescribed with regard to the wire 102 of the stent 100. Additionally,the flow-diverting layer 202 can be formed by laser cutting or etching athin tube.

In the present example, the distal and proximal ends of theflow-diverting layer 202 are perpendicular relative to the length of thelayer 202. However, these ends may also be angled relatively to thelength of layer 202 in a matching, opposite or irregular angularconfiguration.

As best seen in FIGS. 13 and 14, the proximal end of the dual layerstent 200 includes a plurality of attachment members 206 that connectthe anchoring stent 100 with the flow-diverting layer 202. Theattachment members 206 can be composed of tantalum wire (in this case is0.001″ dia.) and can be attached to portions of wire 102 and wire 202.In another embodiment, the proximal end of the flow-diverting layer 202can be crimped on to the wires 102 of the anchoring stent 100. Inanother embodiment, portions of the stent 100 and flow-diverting layercan be woven through each other for attachment purposes. In yet anotherembodiment, the stent 100 can be formed with eye-loops (e.g., formed vialaser cutting or etching) or similar features sized to allow wires 202to be woven through for attachment purposes.

Since the anchoring stent 100 and the flow-diverting layer 202 may havedifferent weave patterns or weave densities, both will shorten in lengthat different rates as their diameter expands. In this respect, theattachment members 206 are preferably located at or near the proximalend of the anchoring stent 100 and the flow-diverting layer 202 asoriented in the delivery device (i.e., on the end opposite the distaltip member 144). Hence, as the stent 200 is deployed, both the anchoringstent 100 and the flow-diverting layer 202 can decrease in length (orincrease if retracting the stent 200 back into a delivery device), yetremain attached to each other. Alternately, attachment members 206 canbe positioned at one or more locations along the length of the duallayer stent 200 (e.g., at the distal end, both ends, the middle, or atboth ends and the middle region).

In one exemplary embodiment of the stent 200, a flow-diverting layer 202comprises 48 wires with a density of about 145 ppi and fully expands toa diameter of about 3.9 mm. An outer stent 100 comprises a single wirewound in a 2.5 revolution winding pattern and fully expands to adiameter of about 4.5 mm. When both layers 100 and 202 are fullyexpanded, the lengths are about 17 mm and 13 mm respectively. When bothlayers 100 and 202 are compressed on a 0.027 inch region of a deliverydevice, their lengths are about 44 mm and 37 mm respectively. When bothlayers 100 and 202 are expanded within a 3.75 mm vessel, their lengthsare about 33 mm and 21 mm respectively.

In one preferred embodiment of the dual layer stent 200, theflow-diverting layer 202 is composed of wires 204 having a diameterbetween about 0.0005 inch and about 0.0018 inch and the wires 102 of thestent 100 have a diameter between about 0.0018 inch and about 0.0050inch. Therefore, the minimum preferred ratio between the diameter of thewire 102 and wire 204 is about 0.0018 to 0.0018 inch respectively (orabout a 1:1 ratio) and the maximum preferred ratio is about0.0050/0.0005 inch (or about a 10:1).

It should be noted that the dual layer stent 200 can produce a largeramount of radial force (defined as the radial force exerted at about 50%radial compression of a stent) than either the stent 100 or flowdiverting layer 200 alone. This higher radial force allows the duallayer stent 200 to have improved deployment and anchoringcharacteristics. In one exemplary test of a dual layer stent embodiment,the outer stent 100 alone had an average radial force of about 0.13 N,the flow diverting layer 202 alone had an average radial force of about0.05 N and the dual layer stent 200 had an average radial force of about0.26 N. In other words, the average radial force of the stent 200 wasgreater than or equal to that of the flow diverting layer 202 and thestent 100 combined.

It should be noted that the porosity (i.e., the percentage of open spaceto non-open space) in the flow-diverting layer 202 changes as itradially expands. In this respect, a desired porosity or pore size canbe controlled by selecting different sized stents 200 (i.e., stents thatfully expand to different diameters). Table 1 below illustratesdifferent exemplary porosities that the flow-diverting layer 202 canachieve by varying the size of the stent 200 (i.e., its fully expandeddiameter) in a particular target vessel. It should be understood thatmodifying other aspects of the flow-diverting layer 202, such as thenumber of wires used, picks per inch (PPI), or wire size may also modifyporosity. Preferably, the flow-diverting layer 202 has a porositybetween about 45-70% when expanded.

Similar techniques are also possible with regard to the porosity of thestent 100. Preferably, the stent 100 has a porosity when expanded thatis between about 75% and 95% and more preferably a range between about80% and 88%. Put a different way, the stent 100 preferably has a metalsurface area or percentage of metal between about 5% and 25% and morepreferably between 12% and 20%.

TABLE 1 Expansion Size in Porosity of Fully Expanded TargetFlow-Diverting No. of Wires PPI Stent OD (mm) Vessel (mm) Layer 202 48145 2.9 mm Fully Expanded 50% 48 145 2.9 mm 2.75 mm 56% 48 145 2.9 mm2.50 mm 61% 48 145 3.4 mm Fully Expanded 51% 48 145 3.4 mm 3.25 mm 59%48 145 3.4 mm 3.00 mm 64% 48 145 3.9 mm Fully Expanded 52% 48 145 3.9 mm3.75 mm 61% 48 145 3.9 mm 3.50 mm 67%

The stent 100 can be “oversized” or have a larger internal diameterrelative to the outer diameter of the flow-diverting layer 202 when in afully expanded position or a target vessel (having a target diameter).Preferably, the difference between the inner surface of the stent 100and the outer surface of the flow-diverting layer 202 is between about0.1 mm and about 0.6 mm (e.g., a gap between about 0.05 mm and about 0.3mm between the two). Generally, the dual layer stent 200 can be slightlyoversized for a patient's target vessel. In this respect, the outerstent 100 can slightly push into the tissue of the target vessel,allowing the “undersized” flow-diverting layer 202 to maintain a profilethat is relatively close to or even touching the tissue of the vessel.This sizing can allow the stent 100 to better anchor within the vesseland closer contact between the flow-diverting layer 202 and vesseltissue. It should be further noted that this “oversizing” of the duallayer stent 200 can result in about a 10-15% increase in the porosity ofthe flow-diverting layer 202 relative to the fully expanded (andunobstructed) position of the flow-diverting layer 202, as seen in theexemplary data in Table 1.

The dual layer stent 200 can provide improved tracking and deploymentperformance, especially when compared to a stent of similar size andthickness to the flow-diverting layer 202. For example, tests have shownthat a reduced amount of force is needed during deployment or retractionof the dual layer stent 200 from the delivery device in comparison to astent similar to the flow-diverting layer alone. The inclusion of theouter stent 100 as part of the dual layer stent 200 reduces friction inthe delivery system relative to the radial force and porosity of thestent 200.

Preferably, the dual layer stent 200 can be deployed or retracted withbetween about 0.2 lbs and about 0.6 lbs of force. By including the stent100 on the outside of the flow diverting layer 202, the deployment forcecan be reduced between about 10-50% as compared with thedeploying/retracting the flow diverting layer 202 alone (i.e., astandalone layer 202 used by itself as seen in FIG. 19). Since lessdeployment force is required for the dual layer stent 200 as comparedwith a bare flow diverting layer 202, more desirable deliverycharacteristics can be achieved from a deployment device.

One exemplary deployment and retraction force test was performed on anexemplary dual layer stent 200 as seen in FIGS. 12-14 and aflow-diverting layer 202 alone, as shown in FIG. 19. The dual layerstent 200 required an average maximum deployment force of about 0.3 lbsand an average maximum retraction force of about 0.4 lbs. The stent ofonly a flow-diverting layer 202 had an average deployment force of about0.7 lbs. Note that retraction of the flow-diverting layer 202 stent wasnot possible in the tests due to a lack of a locking or releasemechanism (e.g., no coils 106 to contact marker band 140, as seen inFIG. 15). Preferably, the dual layer stent 200 includes differences inthe diameter of the wire 102 of the outer stent 100, similar to thosedescribed for the embodiment of FIGS. 1-10. Specifically, the wire 102making up the middle region of the stent 100 have a reduced diameterwhile the wire 102 at the ends (e.g., at loops 104) have a largerdiameter than the middle region. For example, the middle region can beelectropolished to reduce the diameter of wire 102 while the ends of thestent 100 can be protected from electropolishing, maintaining theiroriginal diameter. Put another way, the thickness of the stent 100 isthinner at a middle region. Note that this reduced thickness in themiddle region is also applicable to embodiments of the outer stent thatdo not use wire (e.g., laser cut tube stent seen in FIG. 16). In testtrials of an exemplary embodiment of the dual layer stent 200 with thisdiameter difference, relatively low deployment and retraction forceswere demonstrated. These lower deployment and retraction forces canprovide desirable tracking, deployment and retraction characteristics.Preferably, the wires 102 of the middle region are between about 0.0003inch and about 0.001 inch smaller in diameter or thickness than thedistal and/or proximal regions of the stent 100. Preferably, the wires102 of the middle region are between about 10% to about 40% smaller indiameter or thickness than the distal and/or proximal regions of thestent 100 and most preferably about 25% smaller.

For example, one embodiment included ends composed of wire 102 having adiameter of about 0.0025 inch and a middle region composed of wire 102having a diameter of about 0.0021 inch. This embodiment averaged amaximum average deployment force of about 0.3 lbs within a range ofabout 0.2-0.4 lbs and a maximum average retraction force of about 0.4lbs within a range of about 0.3-0.4 lbs.

Another embodiment included ends composed of wire 102 having a diameterof about 0.0020 inch and a middle region composed of wire 102 having adiameter of about 0.0028 inch. This embodiment averaged a maximumaverage deployment force of about 0.2 lbs within a range of about0.2-0.3 lbs and a maximum average retraction force of about 0.3 lbs in arange of about 0.3-0.4 lbs.

Another embodiment included ends composed of wire 102 having a diameterof about 0.0021 inch and a middle region composed of wire 102 having adiameter of about 0.0028 inch. This embodiment averaged a maximumaverage deployment force of about 0.4 lbs within a range of about0.3-0.4 lbs and a maximum average retraction force of about 0.6 lbs in arange of about 0.5-0.6 inch.

Turning to FIG. 15, a delivery device 210 is shown according to thepresent invention for deploying the stent 200 within a patient. Thedelivery device 210 is generally similar to the previously describeddelivery device 135, including a sheath 133 disposed over a deliverypusher 130 to maintain the stent 200 in a compressed position overmarker band 140.

As with the previous device, a proximal end 201 of the stent 200 isdisposed over distal marker band 140 and proximal coil members 106 arepositioned between marker bands 136 and 140. The stent 200 can bedeployed by proximally retracting the sheath 201 relative to the pusher130. The stent 200 can also be retracted (if it was not fullydeployed/released) by retracting the pusher 130 in a proximal direction,thereby causing the marker band 140 to contact the proximal coil members106, pulling the stent 200 back into the sheath 133.

As previously described, the proximal end 201 of the stent 200 includesattachment members 206 (not shown in FIG. 15) which connect the stent100 with the flow-diverting layer 202. In this respect, as the sheath133 is proximally retracted during deployment and a distal portion 203of the dual layer stent 200 begins to radially expand, the stent 100 andthe flow-diverting layer 202 can decrease in length at different rates.

A portion of the wire 105 can be woven along the length of the stent 100in a distinctive pattern. This length can correspond to the length andposition of the inner flow diverting layer 202, thereby indicating thelength and position of the inner flow diverting layer 202 to the userduring a procedure.

In another preferred embodiment according to the present invention, theflow-diverting layer 202 may be woven into the anchoring stent 100.

FIG. 16 illustrates another embodiment according to the presentinvention of a dual layer stent 300 comprising an inner flow-divertinglayer 202 and an outer stent 302. Preferably, the outer stent 302 isformed by cutting a pattern (e.g., laser cutting or etching) in a sheetor tube composed of a shape memory material (e.g. Nitinol). FIG. 16illustrates a pattern of a plurality of diamonds along the length of theouter stent 302. However, it should be understood that any cut patternis possible, such as a plurality of connected bands, zig-zag patterns,or wave patterns.

The cross sectional view of the dual layer stent 300 illustrates aplurality of exemplary positions for attachment member 206 to connectthe outer stent 302 and inner flow-diverting layer 202. As with any ofthe previously described embodiments, the attachment members 206 (orother methods of attachment such as welding or adhesive) can be locatedat one or more of the exemplary locations shown. For example, attachmentmembers 206 may be located at the proximal end, distal end, or themiddle. In another example, attachment members 206 can be located atboth the proximal and distal ends. Alternately, no attachment members206 or attachment mechanism are used to attach the inner flow-divertinglayer 202 with the outer stent 302.

FIG. 18 illustrates another embodiment of a dual layer stent 400according to the present invention. The stent 400 comprises an innerflow-diverting layer 202 attached to an outer stent 402. The outer stent402 comprises a plurality of radial, zigzag bands 404 that are bridgedor connected via longitudinal members 406. Preferably, the stent 402 canbe created by welding a plurality of members together, laser cutting oretching this pattern into a sheet or tube, or using vapor depositiontechniques. As with previous embodiments, the flow-diverting layer 202can be attached to the outer stent 402 near the distal end, proximalend, middle region, or any combination of these locations.

As best seen in FIGS. 12 and 13, the flow-diverting layer 202 preferablyhas a length that extends near the ends of the main body portion ofstent 100 and stops near the formation of the loops 104. However, theflow-diverting layer 202 can alternately include any range of lengthsand positions relative to the stent 100. For example, FIG. 20illustrates a dual layer stent 200A in which the flow-diverting layer202 is shorter in length than the stent 100 and longitudinally centeredor symmetrically positioned.

In another example, FIG. 21 illustrates a dual layer stent 200B in whichthe flow-diverting layer 202 is longer in length than the stent 100.While the flow-diverting layer 202 is shown as being longitudinallycentered within the stent 100, asymmetrical positioning of theflow-diverting layer 202 is also contemplated.

In yet another example, FIG. 22 illustrates a dual layer stent 200C inwhich a flow-diverting layer 202 is shorter in length than the stent 100and asymmetrically positioned within the stent 100. In this example, theflow-diverting layer 202 is positioned along the proximal half of thestent 100, however, the flow-diverting layer 202 may also be positionedalong the distal half of the stent 100. While the flow-diverting layer202 is shown extending about one half of the length of the stent 100,the flow-diverting layer 202 may also span one third, one quarter or anyfractional portion of the stent 100.

Turning to FIGS. 23-25, the flow-diverting layer 202 can be composed ofone or more expansile wires 500 or filaments. Preferably, the expansilewires 500 are composed of the previously described wires 204 that arecoated with a hydrogel coating 502 that expands in a patient's vessel.The wires 204 may be composed of a shape memory metal (e.g., nitinol), ashape memory polymer, nylon, PET or even entirely of hydrogel. As seenin FIG. 25, the hydrogel wires 500 can be woven amongst wires 204 whichare not coated with hydrogel. Alternately, partial lengths of the wirescan be coated with hydrogel so as to coat only a specific region of theflow-diverting layer 202 (e.g., the center region).

In any of the previous embodiments, one or more of the stent layers(e.g., stent 100 or flow diverting layer 202) can be mostly composed ofa polymer (e.g., a hydrogel, PET (Dacron), nylon, polyurethane, Teflon,and PGA/PGLA). Generally, a polymer stent can be manufactured by thefree radical polymerization of a liquid prepolymer solution within acontainer of a desired shape.

One exemplary polymer stent manufacturing technique can be seen in FIGS.26-29. Starting with FIG. 26, a generally cylindrical mandrel 602 isplaced within a tube 600. Preferably, the mandrel 602 can create afluid-tight seal on at least one end of the tube 600 and preferably theopposing end of the tube 600 is also closed.

In FIG. 27, a liquid prepolymer is injected into the space between themandrel 602 and the tube 600. Polymerization is induced in theprepolymer solution (e.g., heating at 40-80° C. for 12 hours). Oncepolymerized, the tube 600 and mandrel 602 are removed from the solidpolymer tube 606, shown in FIG. 28. This tube 606 can be washed toeliminate residual monomers and dried over a mandrel to maintain shape.

Finally, the polymer tube 606 can be laser cut, CNC machined, etched orotherwise shaped into a desired pattern, as seen in FIG. 29. The lengthand thickness of the final stent can also be modified during themanufacturing process by changing the diameter or length of the tube 606or the mandrel 602.

In another exemplary stent manufacturing process seen in FIG. 30,centrifugal force is used to disperse the prepolymer solution along theinside of a syringe tube 605. Specifically, a plunger 603 is positionedin the tube 605 and a predetermined amount of prepolymer solution 604 istaken into the syringe tube 605. The syringe tube 605 is connected to amechanism that causes the tube 605 to spin in a horizontal orientationalong a longitudinal axis of the tube 605 (e.g., an overhead stirrerpositioned horizontally with its rotating member connected to the tube605).

Once the tube 605 achieves a sufficient rotational speed (e.g., about1500 rpm), the syringe plunger 603 is pulled toward the end of the tube605, taking in a gas such as air. Since the prepolymer solution now hasmore space to spread out, the centrifugal force causes an even coatingto form on the wall of the tube 605. Polymerization can be initialedusing a heat source (e.g., a heat gun) and then heated (e.g., 40-80° C.for 12 hours). The solid polymer tube can then be removed from the tube605, washed to eliminate residual monomers, dried on a mandrel, and thenlaser cut, CNC machined, etched or otherwise shaped into a desiredpattern.

FIGS. 31-36 illustrate yet another exemplary process for creating apolymer stent according to the present invention. Turning first to FIG.31, a plastic or degradable rod 608 is placed in tube 600 and lueradapters 610 are connected to each opening of the tube 600. The rod 608has an engraved or depressed pattern (e.g., created by laser machining,CNC machining or other suitable method) on its outer surface in thepatter desired for the final stent. When the rod 608 is placed in thetube 600, these patterns form channels that are later filled by theprepolymer 604. In other words, the outer diameter of the rod 608 andthe inner diameter of the tube 600 are such that the prepolymer 604 isprevented from moving outside the channels or patterned area.

As seen FIG. 32, a syringe 612 is inserted into a luer adapter 610 andprepolymer solution 604 is injected into the tube 600 as seen in FIG.33. The prepolymer solution 604 fills into the pattern on the surface ofthe rod 608. The syringe 612 is removed from the luer adapter 610 andpolymerization is completed by heating the prepolymer solution 604(e.g., 40-80° C. for about 12 hours).

The rod 608 is removed from the tube 600 as seen in FIG. 34 and placedin an organic solvent bath 622 as seen in FIG. 35. The organic solventbath 622 dissolves the rod 608, leaving only the polymer stent 622 (FIG.36) having the same pattern as the surface of the rod 608.

It should be noted that different aspects of the stent 622 can becontrolled by changing the pattern on the surface of the rod 608, thediameter of the rod 608 and the tube 600, the length of the rod 608 andtube 600 and similar dimensions. Additional modification is alsopossible by laser cutting, CNC machining, etching, or similar processes.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A stent and stent delivery device comprising: astent having proximal loops with one or more coils wrapped around a wireforming the proximal loops; wherein the one or more coils are laterallyoffset from a middle of each proximal loop such that when the stent isin a collapsed state, the one or more coils are positioned near a veryproximal end of the stent, wherein the proximal loops comprise largerproximal loops and smaller proximal loops relative to each other; apusher used to deliver the stent through a catheter; the pusher having adistal portion with first and second enlarged diameter regions, thefirst and second enlarged diameter regions separated by a reduceddiameter region; wherein the one or more coils are contained within thereduced diameter region with clearance between the one or more coils andthe first and second enlarged diameter regions while the pusher deliversthe stent through the catheter.
 2. The stent and stent delivery deviceof claim 1, wherein the one or more coils are radiopaque.
 3. The stentand stent delivery device of claim 1, wherein the first and secondenlarged diameter regions are radiopaque marker bands.
 4. The stent andstent delivery device of claim 1, wherein the one or more coils aredistal of a proximal end of the stent.
 5. The stent and stent deliverydevice of claim 1, wherein proximal retraction of the pusher causes theone or more coils to contact the first enlarged diameter region.
 6. Thestent and stent delivery device of claim 1, wherein distal pushing ofthe pusher causes the one or more coils to contact the second enlargeddiameter region.
 7. The stent and stent delivery device of claim 1,wherein only the larger proximal loops utilize the one or more coils. 8.A stent and stent delivery device comprising: a stent having proximalloops with a coil wrapped around a portion of one of the proximal loop;wherein the coil of the stent is formed from a wire braided into thestent; a pusher used to deliver the stent through a catheter; the pusherhaving a distal portion with first and second enlarged diameter regions,the first and second enlarged diameter regions separated by a reduceddiameter region; wherein the coil is contained within the reduceddiameter region while the pusher delivers the stent through thecatheter.
 9. The stent and stent delivery device of claim 8, furthercomprising a plurality of coils that are each wrapped around a portionof each of the proximal loops.
 10. The stent and stent delivery deviceof claim 9, wherein the the plurality of coils are contained within thereduced diameter region with clearance between the one or more coils andthe first and second enlarged diameter regions while the pusher deliversthe stent through the catheter.
 11. The stent and stent delivery deviceof claim 9, wherein the plurality of coils are distal of a proximal endof the stent.
 12. The stent and stent delivery device of claim 8,wherein the stent is a single layer stent.
 13. The stent and stentdelivery device of claim 8, wherein the proximal loops further compriseat least three longer proximal loops and at least three shorter proximalloops, where each longer proximal loop has a shorter proximal loop oneither side.
 14. The stent and stent delivery device of claim 8, whereinthe stent is a dual layer stent, and an outer layer of the dual layerstent utilizes the proximal loops.
 15. The stent and stent deliverydevice of claim 14, wherein the outer layer of the dual layer stent iswoven from a single wire.
 16. A stent and stent delivery devicecomprising: a stent having proximal loops including shorter proximalloops and longer proximal loops, with a coil wrapped around each longerproximal loop; a pusher used to deliver the stent through a catheter;the pusher having a distal portion with first and second enlargeddiameter regions, the first and second enlarged diameter regionsseparated by a reduced diameter region; wherein the longer proximal loopcoils are contained within the reduced diameter region while the pusherdelivers the stent through the catheter; wherein the coil is a proximalend of a wire woven into the stent.
 17. The stent and stent deliverydevice of claim 16, wherein the stent has distal loops including shorterdistal loops and longer distal loops, and a distal end of the wire is acoil wrapped around one of the longer distal loops of the stent.
 18. Astent and stent delivery device comprising: a stent having proximalloops with one or more coils wrapped around a wire forming the proximalloops; wherein the one or more coils are laterally offset from a middleof each proximal loop such that when the stent is in a collapsed state,the one or more coils are positioned near a very proximal end of thestent, wherein the stent has a plurality of distal loops, with somelarger distal loops and some smaller distal loops; a pusher used todeliver the stent through a catheter; the pusher having a distal portionwith first and second enlarged diameter regions, the first and secondenlarged diameter regions separated by a reduced diameter region;wherein the one or more coils are contained within the reduced diameterregion with clearance between the one or more coils and the first andsecond enlarged diameter regions while the pusher delivers the stentthrough the catheter.
 19. The stent and stent delivery device of claim18, wherein the larger distal loops utilize the one or more coils whilethe smaller distal loops do not.